It is a vagina thats been used and abused. Origin is the North American Turkey , under it's beak is its wattle and it hangs down and flip-flops around when it walks. This is precisely what happens to a womans labia majora after being excessively stretched on numerous occasions after intense and frequent prior sexual encounters. Whether or not the Turkey Wattle is a desirable trait; is in the eyes of the beholder but in most circumstances it is not viewed favorably.
Example set in a dialogue:
Friend 1 : " How was hooking up with that girl the other night ?"
Friend 2 : " That girl was hot but her Turkey Wattle was like down to her knees"